1. Field of the Invention
The invention relates to a process for preparing a catalyst composition, the catalyst composition thus obtained and the use of the composition in hydroprocessing applications.
2. Discussion of the Prior Art
Catalysts comprising at least one Group VIII non-noble metal component and at least two Group VIB metal components, the Group VIII and Group VIB metal components making up at least 50 wt. % of the catalyst composition, calculated as oxides, are known in the art.
U.S. Pat. No. 4,596,785 describes a catalyst composition comprising the disulfides of at least one Group VIII non-noble metal and at least one Group VIB metal. U.S. Pat. No. 4,820,677 describes a catalyst comprising an amorphous sulfide comprising iron as the Group VIII non-noble metal and a metal selected from molybdenum, tungsten or mixtures thereof as the Group VIB metal, as well as a polydentate ligand such as ethylene diamine. In both references the catalyst is prepared via the co-precipitation of water-soluble sources of one Group VIII non-noble metal and two Group VIB metals in the presence of sulfides. The precipitate is isolated, dried, and calcined in an inert atmosphere. The catalysts of these references are binder-free or contain an inorganic oxidic binder, such as alumina.
U.S. Pat. No. 3,678,124 discloses oxidic catalysts to be used in the oxidative dehydrogenation of paraffin hydrocarbons. The catalysts are prepared by co-precipitating water-soluble components of the Group VIB metals and Group VIII non-noble metals. The catalysts are binder-free or contain an oxidic binder such as alumina.
In WO 9903578 catalysts are prepared by co-precipitating specified amounts of a nickel, molybdenum, and tungsten source in the absence of sulfides. The catalyst is binder-free or may contain an oxidic binder such as alumina.
Non-prepublished international patent application PCT/EP00/00354 (corresponds to U.S. patent application Ser. No. 09/482,811, filed Jan. 13, 2000, incorporated herein by reference thereto) describes the preparation of sulfided catalyst compositions by coprecipitation of at least one Group VIII non-noble metal component and at least two Group VIB metal components to form an oxygen-stable precipitate, which is subsequently sulfided. Non-prepublished international patent application PCT/EP00/00355 (corresponds to U.S. patent application Ser. No. 09/231,118, filed Jan. 15, 1999, incorporated herein by reference thereto) describes the preparation of a catalyst composition by contacting at least one Group VIII non-noble metal component and at least two Group VIB metal components in the presence of a protic liquid, wherein at least one of the metal components is at least partly in the solid state during contacting. The catalysts of non-prepublished international patent applications PCT/EP00/00354 and PCT/EP00/00355 are either binder-free or may contain an oxidic binder such as alumina.
It has appeared that binder-free catalysts containing a Group VIII metal component and at least two Group VIB metal components are often difficult to prepare. More in particular, it is difficult to prepare shaped particles with sufficient strength without the help of a binder.
Catalysts containing, e.g., carbon as carrier are known in the art. They are described in JP laid-open patent application 1986-22071, JP laid-open patent application 1986-101247, JP laid-open patent application 1985-58239 and U.S. Pat. No. 5,576,261.
On the other hand, catalysts containing a binder of a refractory oxide such as alumina or silica encounter problems when the catalyst has to be disposed of or recycled. In that case, the first step is often to separate the metal components from the inorganic binder, e.g., by subsequent Teachings with NaOH and H2SO4. However, such a recycling process is time consuming and expensive. Additionally, it cannot be avoided that a portion of the expensive Group VIB and Group VIII metals remains on the binder and is thus lost.
It is therefore an object of the present invention to provide a catalyst comprising at least one Group VIII non-noble metal component and at least two Group VIB metal components, the Group VIII and Group VIB metal components making up at least about 50 wt. % of the catalyst composition, calculated as oxides, which are both easy to prepare and can easily be recycled after use.